Tamoxifen not effective for some breast cancers

Although BRCA2-positive women who use tamoxifen may be less likely to develop breast cancer than those using a placebo, BRCA1-positive women derive no protection from the drug.

Researchers from the University of Washington in Seattle studied 19 women with BRCA1 or BRCA2 gene mutations who participated in the Breast Cancer Prevention Trial (BCPT), part of the National Surgical Adjuvant Breast and Bowel Project.

In that trial, cancer-free high-risk women, 35 years of age or older, were randomly allocated to receive tamoxifen or placebo as a cancer-prevention agent.

For the 11 women with the BRCA2 mutation, using tamoxifen was tied to a 62 per cent reduction in breast cancer risk due to, say the researchers, a reduction in the incidence of oestrogen receptor-positive cancer.

But for the eight women with BRCA1 mutation (in other words, 42 per cent of the women in the study), tamoxifen did not lower the breast cancer risk (JAMA, 2001; 286: 2251-6).